In recent years, regarding an image reading apparatus such as a copying machine, a facsimile machine and a scanner, research and development of a product corresponding to colorization and a product with higher-resolution are progressing. As an outcome of such research and development, various high-performance products are being provided to the market.
An image reading apparatus reads image information for each of three primary colors, that is, red, green and blue. Then, color image information is created by overlapping the image information of each read primary color by a pixel unit.
The image reading apparatus reads image information, such as not only a sheet shaped manuscript but a book with a certain degree thickness are read.
For example, Japanese Patent Application Laid-Open No. 1995-319077 discloses an image reading apparatus equipped with an optical device which reads the image information by a linear image sensor scanning a manuscript placed on the platen glass.
This optical device includes an optical lens and a mirror and the like in addition to the linear image sensor, and is arranged in a position under the platen glass. Rails which guide the optical device are also arranged under the platen glass. And the optical device is reciprocated on the rails when the manuscript reads.
At that time, the mirror of the optical device may vibrate by vibration which occurs by friction between the optical device and the rails. The vibration of the mirror may shift a path of light which enters the linear image sensor.
On the other hand, Japanese Patent Application Laid-Open No. 2005-309301 discloses technology which suppresses vibration of a mirror by holding an edge or the like of the mirror. However, Japanese Patent Application Laid-Open No. 2005-309301 does not disclose by what kind of a method, a construction and a force the edge or the like of the mirror is held.